Notes on the Bible, by Albert Barnes, [1834], at sacred-texts.com
David's growing importance, fugitive as he was, is marked by this appeal to him for deliverance from the Philistines. The "threshing floors" were the natural objects of plunder Jdg 6:11. Keilah was in the Shephelah (marginal reference), probably close to the Philistine border, but its site is uncertain.
If Gad was with David at the forest of Hareth Sa1 22:5, and there inquired for him of the Lord Sa1 23:2,Sa1 23:4, but did not accompany him to Keilah, and if Abiathar's flight occurred at the time of David's being at Keilah, we have an additional striking instance of God's watchful providential care of David in thus sending Abiathar to supply the place of Gad at so critical a moment.
The conduct of the men of Keilah would be like that of the men of Judah to Samson their deliverer Jdg 15:10-13.
Ziph is placed between Hebron and En-gedi (marginal references). (The "wood" Sa1 23:15 is by Conder taken as a proper name, "Cheresh," and identified with Khoreisa.)
A touching example of mutual fidelity between friends. The humility and unselfish love of Jonathan is apparent in Sa1 23:17.
(Hachilah is thought by Conder to be the long ridge called El Kolah). For Jeshimon, see the margin and Num 21:20.
The plain - The Arabah, the desert tract which extends along the valley of the Jordan from the Dead Sea to the Lake of Gennesareth, now called El-Ghor. The word is now given by the Arabs to the valley between the Dead Sea and the Gulf of Akaba.
Sela-hammahlekoth - See the margin. (Identified by Conder with a narrow and impassable gorge between El Kolah and Maon, called Malaky).
En-gedi (the fountain of the kid), anciently called Hazezon-Tamar Gen 14:7 from the palm-trees which used to grow there, still preserves its name in Ain-Djedy. It is about 200 yards from the Dead Sea, about the center of its western shore. It is marked by great luxuriance of vegetation, though the approach to it is through most dangerous and precipitous passes. The country is full of caverns, which serve as lurking places for outlaws at the present day. One of these, a spacious one called Bir-el-Mauquouchieh, with a well in it suitable for watering sheep, close to the Wady Hasasa, may have been the identical cavern in which David cut off Saul's skirt.